Stencil sheet



UNITED STA TEs, PATENT OFFICE 2,007,154 STENCIL sneer George signor to E.

Burt Bradshaw, Wilmington, DeL, as- I. do Pont'de Nemours a Company, Wilmington, DeL, a corporation of Delaware No Drawing.

Application December 2'1, 1935,

Serial No. 56,320

5Claims.

This inventionrelates to new and useful improvements in flexible articles and has more particular reference to the production ofstencil sheets such as those employed in .the reduplica- -5jtion of manuscripts, drawings, typewritten or similar matter, through impact of type, impress of stylus 'or by other suitable means upon a'surface or facing ofa blank stencil sheet. t

More particularly the invention is directed to the production of flexible stencil sheets coated, surfaced, or impregnated with a polymerizable substance containing as a constituent thereof a polymer or interpolymer of an acrylic acid derivative, such as the esters, amides, anhydrides,

l5 anilides, etc. a a

' In a more specific sense the invention is concerned with the employment of the polymers or lnterpolymers of alpha-substituted acrylic acid derivatives, such as the alpha-substituted acrylic M acid esters, amides, anhydrides, chlorides, ani- 'iides, etc. as coating and/or impregnating sub-x stances in astencil sheet.

In a specific and preferred embodiment of the invention methyl methacrylate polymers or interpolymei's'. are em-z 2| ployed as the coating and/or impregnating agent for said flexible stencil sheet articles.

In the manufacture of stencil sheets heretofore,

the practice has been to coat or impregnate a 1 suitable sheet or open-texture, porous base ma- 10 'terial, such as bibulous or yoshinopaper, or the like, with soft wax or; gelatin, or with a cellulosic substance such as cellulose nitrate or-acetate in solution with avolatile solvent. The resultant. articles from. such prior practice, particularly as in instances where gelatin or wax reagents are finployed possess many disadvantages, includamong others, anjobjectionable stickiness on handilngJacking cient softness or pliability, and prone to become brittle when stored or sub- -iected'to non-use for prolonged periods-of time.

as other disadvantages existing in prior art sheets, [and to provide a stencil sheet adapted to greater efilclency 'and possessed of improvedcharacter i'stics in texture, finish, flexibility and softness.

In adapting the invention commercially any suitable type .or conventional form of fibrous, open-texture, porousbase sheet material, such It is among the objects of the-present inve'n' tion, therefore, to overcome the foregoing, as well astheyoshino paper referred to, may be advan- ,meric, alpha-substituted acrylic acid esters, such as the, alpha-alkyl and alpha-aryl acrylic acid esters. Among spe'cificexamples of these may be mentioned the esters of alpha-phenyl acrylic acid, alpha-ethyl acrylic acid, alpha-butyl acrylic acid, and alpha-methyl acrylic acid. Of this group, alpha-methyl acrylic acid esters Will be found preferable, in view of their greater ease I and adaptability to polymerization; and in general, most beneficial results will be procured when alpha-methyl methacrylate is employed as one specific ester. Additionally, in rpOlymers ofthe different esters of acrylic oralpha-substituted acrylic acid, particularly inter-polymers of diflerent or unlike .esters of acrylic or alpha-methyl acrylic acid,

may 'be advantageously employed in the invention. Examples of such inter-polymers include those of methyl methacrylate and'isobutyl methacrylate, methyl methacrylate and n-propyl methacrylate'n iethyl methacrylate and cyclohexyl methaorylate, methyl acrylate and methyl methacrylate, etc. These interpolymersmay beobtained in'accordance with the processes described in the co-pending application of Harold J. Barrett, Serial No. 50,711, filed November 20, d 1935. In order that the invention may be moreclearly understood, the following specific examples are given wherein the proportions and parts set out are all by weight:

Parts Methyl methacryiate polymer (high vis- Acetone g 15; rButy'l acetate 50 "Rename i g Ethyl acetate..e-

It is to be understood, ofcourse, that the foregoing examples merely illustrative of wone specific embodiment and that the invention is to'be in no wise limited thereby since, obviously, variance in the proportions and ingredients employed may be resorted to without departure from the spirit or scope of the invention.-

-In carrying the-invention into effect the ingredients employed in and going to make up the ultimate, polymerized coating and/or impregnating composition may be admixed or incorporated with each other to form a solution by thereafter removing any excess thereof from-such material in any suitable manner. Thereafter,"

the coating and/or impregnating operation may be completed by applying pressure upon .the treated material in the presence or absence of heat as desired or the sheet otherwise trea to eifect its drying preparatory to use. In lieu of employing directly the acrylic acid derivative Polymer, it may be advantageous to treat the base material with compositions analogous to those of the examples containing the monomer, preferably in the presence of a polymerization catalyst such as benzoyl peroxide, and thereafter subjecting the article to polymerizing conditions, e. g., heat and/or light. Irrespective of whether the original composition contains monomer-and/or polymer, it is to be understood that the auxiliary constituents thereof should be so selected and apportioned that a homogeneous composition will result. an ingredient of the coating and/or impregnating composition, mono or polyhydric al- 1 cohols or their substitution compounds, such as mono-ethyl ether of ethylene glycol, or the like,

may be employed, whereby permanent softenigg and flexibility characteristics may be impart to the resultant sheet. .Similarly, various tempering agents, such as olive oil, castor oilfas 45 well as numerous penetrating, homogenizing,

and/or dispersing agents, may beemployed as ingredients of the composition. These latter agents include the higher olecular weight fatty alcohols and their derivaifies containing -six or more carbon atoms. Among specific examples oi'th'e alcohols so included may be, the higher molecular weight saturated primary alcohols s ich as octyl, decyl, dodecyl, tetradecyl, cetyl, octadecyl, eicosyl, etc.; unsaturated primary'alcohols such as decenyl, tetradecenyl, 9,10-octa-f decenyl. eicosenyl, etc.; cyclo aliphatic alcohols such as the naphthenyl alcohols; ethers of glycols andpolyhydric alcohols, such as the nat-'- .urally occurring selachyl alcohol (glycerinei mono-octadecenyl ether), batyl alcohol (glycerine mono-octadecyl ether) and chimyl alcohol (glycerine monocetyl ether) as well as synthetic I etherssuch'as ethylene glycol inonocetylether,

poly-glycerine mono-tetradecyl ether; etc.; as

well as poly ydric alcohols such octadecenediol, and octadecanediol, might alsobe mentioned. Eurthermore, suitable solvents, such sweetener methyl acetone, toluol, benzol, ethyl acetate,

butyl acetate, etc., or mixtures thereof, may be suitably selected and advantageously employed in the coating composition. Additionally desired and suitable stabilizers. such as fatty acid anhydrides, including those of lauric, myristic,

palmitic, stearie, cocoanut oil fatty acids, sperm oil'fatty acids, etc., may likewise be employed in the coating composition, whereby a tough and impervious sheet will result. Also, in order to render-the coated sheet readily penetrable to the cutting effect of one or stylus pressure, suitable proportions of glycerin triacetate and analogous compounds may be employed, if desired, in the .ooating composition.

Furthermore, it may be desirable to frequently incorporate one or more plasticizersand/or softeners in the coating solution, whereby the prop-' ertles of the'resultantstencil sheet may be varied and controlled to any desired degree. Among plasticizers and softeners suitable for such purpose may bementioned the phthalates, such as dibutyl phthalate, diethyl phthalate, cycloheiwl butyl phthalate, dimethoxyethyl adipate, etc.

, However, in instances where the higher alphaalkyl acrylic acid esters are employed in the invention, it will be found preferable if little or' noplasticizer is employed, sincethese esters lack the desired property of ready and easy pol erlzation which" the alpha methyl acrylic a d esters possess.

Other desired solvents, plasticizers, softening and/or dispersing agents may be similarly employed in the invention suchas those-more particularly set forth and described in the patent of Daniel E. Strain, N0. 2,046,886, issued July As many widely diil'erent and varied embodiments of the invention may be had without departing from its spirit and scope, it is to be understood that the invention is not to be limited to, the embodiments. hereinbeiore set out, but only as defined in the appended claims.

I claim as my invention: l

1. A stencil sheet, comprising an ink permeable base sheet having a coating of ai'plasticiaer and methyl methacrylate, said coated sheet being capable of being cut by type.

2, A stencil sheet, comprising an ink permeable base sheet having a coating of a plasticizer and polymerized methyl methacrylate, said coated sheet being capable of being cut by type. 8.- A stencil sheet comprising a flexible, ink permeable base sheet having a coating of a plasticizer and-a methyl methacrylate polymer, said coated sheet being capable of being cut by tm 4. A- stencil sheet comprising a flexible, ink permeable base sheet having a coating of a plasticizer and a methyl methaorylate inter- Polymer, said coated sheet being capable of be-.

ing out by type.

15; A sheet comprising" a flexible, ink 

